WASHINGTON — The Air Force's decision to pick a larger European plane to replace its current fleet of aerial refueling tankers could cost millions of dollars in construction costs for new hangars, longer runways and strengthened taxi ramps, two senators said Wednesday.

"The entire selection process has raised serious questions and will add hundreds of millions of dollars in military construction (costs)," said Sen. Kit Bond, R-Mo. The Boeing Co., which is protesting the Air Force award, has its defense division in St. Louis.

Air Force Secretary Michael Wynne again defended the Air Force's decision to award a $35 billion tanker contract to Northrop Grumman and the European Aeronautic Defense and Space Co., the parent company of Boeing rival Airbus.

The Northrop-EADS tanker will use an Airbus A330, which is larger than the 767 tankers that Boeing offered in the competition.

After the hearing, Sen. Patty Murray, D-Wash., said it was her understanding that the Air Force hadn't considered military construction costs in evaluating the Northrop-EADS and Boeing bids.

"These things need to be taken into account," Murray said.

Wynne said that the Air Force has followed all procurement regulations and that the competition had been fair and open.

"We bought the right airplane at the right price," he said.

Air Force Chief of Staff Gen. T. Michael Moseley, who also testified, agreed.

"We got a good airplane I am ready to fly," Moseley said.

Wynne did say that he was concerned about the nation's shrinking defense industrial base, but he added that the Air Force was barred from considering that in awarding the tanker contract.

The Air Force's award of the contract to Northrup-EADS has been widely criticized on Capitol Hill. A330s are usually assembled in Toulouse, France, using French, German, British and Spanish parts. The tanker version will be assembled in Mobile, Ala., where Northrop-EADS said it will build a plant.

The Boeing 767 tankers would be built in Everett, Wash., with the tanker equipment added and flight testing conducted in Wichita, Kan.

Some on the subcommittee praised the selection of the European tanker.

"It's clearly the best tanker to meet the Air Force's needs," said Sen. Richard Shelby, R-Ala. "The prime contractor that won, Northrop Grumman, is headquartered in Los Angeles. It is no less an American company than Boeing."